The invention relates to a motor vehicle having a windshield with lateral end sections provided with chassis (body) pillars.
Such motor vehicles are well-known and have a plurality of chassis pillars that form the so-called “greenhouse,” that is, the area of the passenger compartment above the shoulder line. When the prior art vehicles are moving, the deflection of the air flow causes a flow separation in the area of the front chassis pillars, hereinafter also referred to as the A pillars. The resulting separation region, also called the “A pillar vortex,” has a highly variable characteristic as a function of the tilt and/or camber of the windshield. The steeper the windshield in relation to the horizontal plane and/or the less cambered the windshield, the larger the separation region. The separation region causes vortices with a high negative pressure in the vortex core and, hence, considerable air flow losses in the area of the greenhouse that in turn leads to an increase in the cw value of the motor vehicle and an increase in the rear axle lift. The vortices occur primarily in the lower and middle area of the A pillar, that is, in the area, in which the outside rear mirror is usually attached.
The object of the invention is to improve the aerodynamic properties of motor vehicles of the above-described type.
This and other objects are achieved with a motor vehicle having a windshield with lateral end sections provided with chassis pillars, in which an oblong opening is provided between at least one lateral end section of the windshield and the adjacent chassis pillar.
In accordance with the invention, a “through flow” is enabled of at least one lateral end section of the windshield of the motor vehicle by providing an opening between the windshield and the chassis pillar. The flow (air stream) that is generated by the moving vehicle is channeled through this opening. In this way, the flow is returned in a defined manner into an air stream that flows snugly around the greenhouse. Thus, the flow through the opening at the A pillar results in a reduction in the separation region in the lateral area of the motor vehicle. This feature weakens the vortices in the area of the A pillar, as a result of which the cw value of the motor vehicle is reduced and the rear axle lift is minimized. In addition, the flow around the outside rear mirror, which is mounted in the area of the A pillar, is improved.
Of course, it is well-known to guide the air that flows around the motor vehicle between the lateral end sections of the rear window and the rear chassis pillar, also called the “C pillar.” This strategy is implemented, for example, in the Ferrari 599 GTB vehicle and the Ford Iosis Max concept vehicle. However, the C pillar in the prior art motor vehicles only acts as an air flow guiding element that guides the flow in the direction of the rear window and/or the rear hatch opening or, more specifically, the trunk lid, in order to achieve a flow that remains, as long as possible, in the rear hatch area of the motor vehicle and, in so doing, reduces the size of the dead water zone in the area of the rear window. As a result, the known motor vehicles do not provide any indication of the solution according to the invention.
The opening is configured comparatively narrow and oblong along the course of the A pillar, thus, in the form of a slot or a gap. Preferably, both the right and the left end sections of the windshield have an opening. However, it is, of course, also possible to provide an opening on only one side of the vehicle.
The size of the opening can remain constant along the vertical extent of the A pillar. Preferably, the width of the opening tapers off upwards, so that a passage for the flowing air is created in the manner of an upwardly narrowing channel. Of course, the width of the opening along the course of the A pillar can also vary elsewhere.
The opening begins preferably at the lower end of the A pillar, at the so-called A pillar root, and extends preferably upwards as far as about the middle of the vertical extent of the A pillar, because the air flowing around this area exhibits especially strong turbulence. However, the opening can also extend even further upwards.
Preferably, the channel-shaped opening extends continuously upwards from the A pillar root. Of course, the passage for the flow air can also be implemented with two or more adjacent openings by providing one or more transverse members between the lateral end section and the A pillar, for example, in order to increase the rigidity of the A pillar. The transverse members can be adhesively cemented, for example, to the windshield or screwed to the windshield by means of bore holes in the windshield.
Preferably, the A pillar is configured as an airfoil profile. In airfoil profiles the front edge forms a negative pressure area (“suction peak”) that generates a force directed opposite the direction of travel and thereby reduces in total the air resistance of the motor vehicle.
The A pillar is preferably configured as a hollow body having a closed cross-section. However, an open profile can also be connected to the windshield, but not exclusively with such A pillars that have no bearing function (see the following explanation).
The cross-sectional shape and/or the size of the cross-sectional area of the A pillar can remain constant along the course of the A pillar or can vary along the A pillar. In the case of an airfoil-like cross-section of the A pillar, the angle, at which the ligament of the airfoil profile is arranged relative to the transverse direction of the motor vehicle and/or the horizontal plane, can remain constant or vary along the vertical extent of the A pillar. When the angle changes, the result is an A pillar that turns in on itself.
The A pillar can be adapted to the respective flow topology of the motor vehicle concerned by means of the geometric configuration. The geometric design is carried out on the basis of measurements (wind tunnel, road test, etc.) or numerical simulation.
In the context of the present invention, the term “A pillar” is defined as any device that is connected to the lateral end sections of the windshield. This definition also includes such elements of the invention that do not have a bearing function. Such elements are configured, for example, as the trim parts with air flow guiding properties (“layer”). Since they do not have a bearing function, it is not necessary that they be connected to the region of the front hood or to the roof of the motor vehicle. Naturally another bearing element has to be provided for a motor vehicle with such non-bearing elements. This bearing element, which has to be provided as an alternative, can be formed, for example, by a so-called “cage”, as known, for example, from the touring car sport. A component of this cage is disposed behind the windshield and rigidly connected to the floor of the motor vehicle chassis. As a result, the windshield bears exclusively the forces generated by the air stream, for which reason the windshield may be changed, if desired, as a function of its design and material strength. As an alternative, the elements that bear by way of replacement may also be constructed in the form of a pillar, which is covered by the lateral end sections of the windshield and which is not perceived or not perceived at first glance from outside the motor vehicle.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.